This invention relates to flexible hoses, and more particularly to flexible helically wound two-piece construction hoses, which can be used with vacuum cleaners and for other applications.
Flexible helically wound two-piece construction hoses are known. These include hoses having an inner base strip with a generally U-shaped cross section. The base strip is helically wound to form a tube, with opposite walls of the U-shaped cross section forming a helical radially outwardly extending rib where adjacent convolutions abut. Such hoses also have an outer cap strip which is also elongated and also has a generally U-shape cross section. The cap strip is helically wound about the rib of the tube formed by the wound base strip, with opposite walls of the U-shaped cross section of the cap portion extending radially inwardly toward the longitudinal axis of the tube on either side of the rib. The cap strip thereby holds together the two walls of the base strip which form the rib, maintaining itself and the base strip in tubular form. The cap strip is secured to the rib by a binding material, which could be a hot melt plastic, which fills the space between the rib and the cap and, in some cases, extends part of the way into the space between the walls that form the rib.
When a helically wound dual profile hose is flexed, the flexing action includes a spreading of the walls that form the rib in the portion of the rib inward of the cap structure. In some of the previously known helically wound two-piece construction hoses, the cap structure also will flex if the walls are spread under extreme axial tension. In others, the cap structure, especially when filled with the binding material, is rigid. Rigidity of the cap has been considered necessary in these latter hoses in order to resist crushing and kinking of the hose and to provide abrasion resistance. However, the rigidity of the cap limits the degree to which the walls that form the rib can spread, thereby limiting the flexibility of the hose.